May 19 is the third annual National Hepatitis Testing Day, an opportunity to raise awareness among healthcare providers and the public about screening for hepatitis B and C. According to the Centers for Disease Control and Prevention (CDC), among the approximately 3 million people with hepatitis C in the U.S., an estimated 75% do not know they are infected.

Over years or decades, chronic hepatitis B or C can lead to severe liver disease including cirrhosis and liver cancer, and viral hepatitis is a leading indication for liver transplants worldwide.

Hepatitis B -- along with hepatitis A, which does not lead to chronic disease -- can be prevented by a vaccine. The hepatitis B vaccine is included as a routine childhood immunization. The vaccine is also recommended for people at risk who were not immunized as children, including people who inject drugs, people who have sex with multiple partners, gay and bisexual men, people with HIV, people with other chronic liver diseases (including hepatitis C), patients undergoing kidney dialysis, people with diabetes, prisoners, and healthcare or emergency service workers.

There is currently no vaccine for hepatitis C, but new direct-acting antiviral treatments can cure most patients without interferon. The CDC and U.S. Preventive Services Task Force recommend that all Baby Boomers born between 1945 and 1965 should be screened for HCV at least once as part of their routine health care.